Adding CoreOS support

[Cody Bunch]

Would love to add this:

https://coreos.com/docs/running-coreos/bare-metal/booting-with-pxe/

As it uses cloud-init, I figure passing that along instead of the generic postinstall.sh as usually gets generated should work. The downside, however, is it is an in-ram system, so, on subsequent boots when other's would boot from disk, I'm not sure how that would be handled.

Thoughts?

[Joseph Callen]

I am certainly a Hanlon and Ruby novice but I would figure that you would need to create new model for CoreOS.  Then the state machine would just more or less loop back to something like an "OS install" each run.  After looking at the base ubuntu model doesn't seem like it would be too bad.